Embodiments of the invention relate to methods and devices and, more particularly, to mechanisms and techniques for more precisely controlling, with less applied force, inlet guide vanes of turbo-machinery.
Turbo-machinery generally has internal rotating components, typically inlet guide vanes (IGV) for example, which are adjusted based on the operating conditions of the turbo-machinery. In an automated system, adjusting the inlet guide vanes requires the use of an actuator attached to an actuator rod connected to an actuator ring operating a four bar mechanism or a slotted nozzle driven in rotation by fixed pins on the actuation ring. In available inlet guide vane solutions, as shown prior art FIG. 1, the inlet guide vane's control components for adjusting the vanes are positioned in different parallel planes. For example, looking to FIG. 1, the four bar mechanism 108 is on a plane between the plane of the vanes 106 and the plane of actuation ring 104 where the actuator rod connects to a pin 102 on the actuation ring 104. In another example, prior art FIG. 2 depicts a slotted nozzle driven inlet guide vane assembly with the actuator 208, the actuation ring 204 and the levers operating the vanes 206 in different planes.
The currently available designs result in several problems experienced during operation. With regard to the four bar system, the force applied to the actuate the vanes is in a different plane than the actuator ring and the four bar mechanism and is therefore non-symmetrically applied with respect to the bushings and connection points between the actuation rod, actuation ring and the four bar mechanism. Accordingly, a bending force is exerted on the actuation rod increasing the force necessary to rotate the actuation ring and stickling of the connection components. Similarly, the slotted nozzle system as illustrated in FIG. 2, develops guide ring fretting leading to increased actuation force requirements, jamming and gain hunting. For both mechanisms, a desirable characteristic would also include a more compact design of the inlet guide vane system leading to both a reduction in mass and a reduction in the force necessary to operate the inlet guide vane system. A detailed description of the construction and operation of a prior art inlet guide vane system is presented in U.S. patent application Ser. No. 12/415,417 incorporated herein by reference.
Accordingly, it would be desirable to provide devices and methods that avoid the afore-described problems and drawbacks.